1. Field of the Invention
This invention relates to a method and apparatus for alignment of individual fibers in a known direction. This method and apparatus are fundamental to the development of the technology for production of fiber-woven garments with qualities like those made from yarn-woven fabrics and offer increased productivity and reduced material waste and energy consumption as compared with conventional processes of spinning staple fibers into yarn, of weaving yarn into fabric, and of tailoring garments from fabrics.
Staple fibers must be arranged in orderly patterns to produce fiber-woven fabrics with aesthetic and performance characteristics comparable to conventional woven fabrics. The fibers in the final fabric are oriented principally in two perpendicular directions so that the fibers retain bending and sliding characteristics similar to those of warp and fill yarns in conventional woven fabric.
The processes of separating, aligning (or paralleling), and depositing the fibers provide the main problems in producing fiber-woven garments. The present invention pertains to the fiber alignment part of the overall process.
2. Description of the Prior Art
Studies have been made of the movement of fibers by air flows for textile-industry related applications, some of which relate to general problems of fiber transport, with others being concerned with particular devices for producing nonwoven fabrics. As such, the same are not concerned at all with fiber alignment, but instead seek to form an isotropic fiber web. The work of Edberg, "A Basic Investigation of the Behavior of Cotton Fibers Subjected to Aerodynamic Forces", Studies in Modern Yarn Production 1968, pp. 96-108, is related to the problems of orienting as well as transporting fibers. In this study, air flows with fibers were observed in straight ducts which had different degrees of convergence, and it was discovered that large percentages of the fibers could be made parallel. To do so, however, required high air speeds (30 to 100 m/sec) which is undesirable for the ordered deposition of the fibers.
The patent to Jakas and Mullin ("Fiber Aligning Apparatus", U.S. Pat. No. 3,619,869, Nov. 1971) describes an apparatus in which fibers move in an accelerating air flow through a cone, and pass out of the cone through a slot and onto a moving screen. The slot width is less than the fiber length, while the slot length is greater than the fiber length. Another patent, by Marshall and Silvi ("Reorientation of Fibers in a Fluid Stream", U.S. Pat. No. 3,812,553, May 1974), also relates to fiber alignment. In this case a high-velocity fluid stream carrying fibers is formed, then decelerated to form a wide but shallow stream, and then deflected by a downward-curving wall. It is stated that this causes the fibers to be oriented in a direction substantially perpendicular to the flow direction. Specific results cited are in terms of the ratio of cross-direction to machine-direction strength of the web.